einforced polyamides and process of preparation thereof

ABSTRACT

1. A reinforced polymeric composition comprising a polyamide and at least about 25% by volume of an inorganic filler material having a length to diameter ratio of up to about 25 to 1, said material having been treated with an organosilane coupling agent of the formula   WHERE X is a hydrolyzable group capable of reaction with a hydroxyl group, Y is hydrogen or a monovalent hydrocarbon group, R is an alkylene group having from 1 to about 20 carbon atoms, Z is a group capable of reaction with a polyamide, n is an integer from 0 to 1, a is an integer from 1 to 3, b is an integer from 0 to 2, c is an integer from 1 to 3 and the sum of a+b+c equals 4. (The present application is a continuation-in-part of copending U.S. application Ser. No. 284,375 filed May 31, 1963, now abandoned.

United States Patent [191 Hedrick et al.

111 E Re. 28,646

[ Reissued Dec. 9, 1975 I 1 REINFORCED POLYAMIDES AND PROCESS OFPREPARATION THEREOF [75] Inventors: Ross Melvin Hedrick, Creve Coeur;

William R. Richard, Jr., St. Louis, both of Mo.

[73] Assignee: Monsanto Company, St. Louis, Mo.

[22] Filed: June 20, 1973 [21] Appl. No.: 372,880

Related US. Patent Documents Reissue of:

[64] Patent No.: 3,419,517

Issued: Dec. 31, 1968 Appl. No.: 560,247 Filed: June 24, 1966 US.Applications: [63] Continuation of Ser. No. 154,451, June 18, 1971,

FOREIGN PATENTS OR APPLICATIONS 6,406,095 12/1964 Netherlands OTHERPUBLICATIONS Anonymous: Plastics Technology, Feb. 42-44.

T. P. Murphy: A.C.S., Div. of Org. Coating and Plastics Chem., paperspresented at Atlantic City Meeting, Sept. 1965, 25(2), pp. 76, 77, 79,83, 85, 89, 90.

J. S. Marsden and S. Sterman: A.C.S. Div. or Org. Coating and PlasticsChem., papers presented at Atlantic City meeting, Sept. 1965, 25 (2);pp. 91, 97-100.

Primary Examiner-Lewis T. Jacobs EXEMPLARY CLAIM l. A reinforcedpolymeric composition comprising a polyamide and at least about 25% byvolume of an inorganic filler material having a length to diameter ratioof up to about 25 to I, said material having been treated with anorganosilane coupling agent of the formula where X is a hydrolyzablegroup capable of reaction with a hydroxyl group, Y is hydrogen or amonovalent hydrocarbon group, R is an alkylene group having from 1 toabout 20 carbon atoms, Z is a group capable of reaction with apolyamide, n is an integer from 0 to l, a is an integer from 1 to 3, bis an integer from 0 to 2, c is an integer from 1 to 3 and the sum of a+b+ c equals 4.

45 Claims, No Drawings REINFORCED POLYAMIDES AND PROCESS OF PREPARATIONTHEREOF Matter enclosed in heavy brackets appears in the original patentbut forms no part of this reissue specification; matter printed initalics indicates the additions made by reissue.

I: The present application is a continuationinpart of copending US.application Ser. No. 284,375 filed May 31, 1963, now abandoned. I

This is a continuation of application Ser. No. 154,451, filed June 18,1971, and now abandoned.

The present application is an application for a reissue of US. 3,419,517issued on Dec. 31, I968. U.S. 3,419,517 issued from US. PatentApplication Ser. No. 560,24 7 filed on June 24, I 966 as acontinuation-in-part of then copending U.S. Patent Application Ser. No.284,375 filed May 31, 1963 and now abandoned.

This invention relates to polyamide compositions reinforced by theinclusion therein of modified particulate materials. One feature of theinvention pertains to reinforced polyamides having mechanical propertiessignificantly improved by comparison to the properties of polyamidesdescribed in the prior art. This invention also relates to processes forpreparing the polyamides referred to above. Another feature of theinvention pertains to a base-catalyzed, substantially anhydrous anionicpolymerization of a lactam monomer in the presence of a modifiedparticulate material. Yet another feature of the invention is directedto a condensation polymerization of a diamine and a dicarboxylic acid inthe presence of a modified particulate material.

It is well known in the prior art that polymeric compositions can befilled with non-polymeric substances to form a uniform finished product.initially, various fillers were used in a polymeric material to colorthe polymer, change its coefficient of expansion, improve abrasionresistance, modulus, and strength, and to dilute the polymer therebylowering its costs. It was, and is now, common practice to admix afiller and polymer in several ways to produce a dispersion of the fillerin the polymer. One method has been to mix thoroughly a monomer andfiller and subsequently poly merize the monomer, thereby producing acomposition wherein the filler is intimately dispersed throughout thefinished product. Another method has been to subject uncured polymer andfiller to a shearing force thereby dispersing the filler in thepolymeric matrix. Various other methods of filling polymers are alsowell known in the art.

However, the upper limit of filler that can be used in such mixtureswithout adversely affecting the mechanical properties of the product islow. The tensile and tlexural strengths particularly fall off sharply atrelatively low concentrations of filler. An exception to thisgeneralization has been the use of fibrous material, particularlyfibrous glass particles, in polymeric compositions. The incorporation offibrous glass into a polymer increases mechanical propertiessignificantly. As yet, such improvement has not been achieved by the useof particulate material. The reason for the decrease in strengthexhibited by particulately filled polymers is that a particulate fillerin a polymer is not a component comparable to a fiber in loaddistribution characteristics. Normally a filler acts to concentratestresses rather than distribute them. As a result, the polymer-fillerinterface is the weak link in the composite. With a fibrous filler, theplurality of weak links along the fiber structure result in a reasonablystrong bond when stress is applied in a direction parallel to theorientation of the fibers. When a transverse stress is applied tolongitudinally oriented fibrous filler or when any stress is applied toparticulate filled materials, the stress is not well distributed and thecomposition is weak. Therefore a filled polymeric product which containsless polymer per unit volume of the product than an unfilled polymer,oridinarily possesses mechanical properties inferior to the unfilledpolymer, particularly at granular filler concentrations of about 50% ormore by weight or 25% or more by volume.

The reinforcement of polyamide compositions by means of particulate asdistinguished from fibrous particles is a desirable feature since aparticulate inorganic-monomer mixture is more fluid, hence more easilycast or molded, than a mixture containing an equivalent amount of afibrous material. Further, fabrication techniques are far simpler for amixture of particulate inorganic and polymer than for a mixture offibers and polymer.

Those skilled in the art will recognize, however, that certain of themechanical properties of polyamides as well as other polymers have inthe past been improved by the inculsion of inorganic particulatematerials within the polymeric matrix. Youngs modulus of elasticity forinstance can be increased by filling a polyamide with a high level ofparticulate inorganic. The flexural and tensile strengths arecompromised, however, as is the resistance to impact, For many uses,what is required is not an improvement in one mechanical property butrather an improvement in a combination of properties. Which combinationof properties should be emphasized for improvement depends upon the usesenvisioned for the final product. For uses such as fu rniture, furniturecomponents, automobile components, equipment housings, building panelsand other applications where the tensile and flexural strengths andmoduli and impact strength are important factors, one value helpful inscreening suitable materials from unsuitable materials is the StrengthIndex. The Strength Index is a property of a material which is basedupon the relationship of the flexural strength to the impact strength ofa material. Generally, the higher the Strength index of a composition,the more valuable it is for several of the uses mentioned above.

It a particulately filled polyamide could be fabricated with a StrengthIndex high enough to permit its use in several applications heretoforeunsuitable for polyamides, the development would certainly represent avaluable and unobvious advance in the art. Providing such aparticulately filled, highly reinforced polyamide constitutes aprincipal object of this invention. Another object is the provision of amethod for preparing polyamides with an unusually high Strength Indexand rigidity. Additional objects, benefits and advantages will becomeapparent in view of the following detailed description.

The polymeric compositions of this invention comprise a polyamide, andat least 25% by volume of an inorganinc filler material having a lengthto diameter ratio of up to 25 to I, said material having been treatedwith an organo-silane coupling agent of the formula where X is ahydrolyzable group capable of reaction with a hydroxyl group, Y ishydrogen or a monovalent hydrocarbon group, R is an alkylene grouphaving from about i to about 20 carbon atoms, Z is a group capable 3freaction with a polyamide, n is an integer from to a is an integer from1 to 3, b is an integer from 0 to c is an integer from 1 to 3 and thesum of a b c nd equals 4.

POLYMER Polyamides useful in the compositions of this invenon includetwo broad categories. One category inludes the polylactams produced bythe polymerization f lactam monomers of the formula here R is analkylene group having from 3 to 12 or note carbon atoms, preferably from5 to 12 carbon :oms. A preferred monomer is e caprolactam. Lacimmonomers in addition to e caprolactam include pyrrolidone, piperidone,valerolactam, caprolactams [her than the e isomer, methyl cyclohexanoneisoxners, capryllactam, cyclodecanone isoxime, lauryllac- 1m, etc. Aspecific polyamide to which this invention applicable ispolycaprolactam, commonly known as ylon 6. Also included are copolymersof two or more fthe above or similar lactam monomers as well ascoolymers containing more than 50% lactam and a naller quantity of othermonomers polymerizable by n anionic, base-catalyzed mechanism. Examplesinlude copolymers of caprolactam with capryllactam, apolymers ofcaprolactam with lauryllactam and coolymers of pyrrolidone withpiperidone or caprolactm as well as copolymers of a lactam with abislactam aving a formula such as the following:

CH,-CH

H, CH,CH,NH

he second category of polyamides comprises those olymers formed by thecondensation polymerization fdicarboxylic acids with diamines, one ofthe most gnificant polymers being polyhexamethylene adipalide (nylon6,6). Other related polyamides include iose formed from polyamines suchas propanediaiine, hexamethylenediamine and octamethylenedia- |ine andpolycarboxylic acids such as adipic acid, pi- |elic acid, suberic acid,sebacic acid and dodecanediic acid. Also included are copolymers orpolyblends of olyamides of the two above categories. The copolylers orpolyblends can consist of mixture of the two rms of polyamides with eachother or with other comatible resin systems. The copolymers orpolyblends of iis invention are limited to those containing at least 0%by weight polyamide. Most of the preferred comositions will contain atleast 90% by weight polyamide l the resin phase. Examples of resinswhich can be lixed with polyamides to form a blend or copolymer icludepolypropylene, polyethylene, polystyrene, olyacrylonitrile,polybutadiene, acrylonitrile-containlg rubbers, styrene-acrylonitrilecopolymer and polyhenylene oxide.

The polyamides may be linear or crosslinked. A rosslinked polyamideprovides some improvement in iechanical properties, particularly impactstrength,

but linear polyamides are also definitely included within the scope ofthe invention. The maximum amount of tolerable crosslinking in thepolymer depends upon the proposed use of the finished composition.Moderate crosslinking produces compositions with high impact resistanceand somewhat diminished flexural strength and modulus. Consequently,control of crosslinking provides a variable which enables one to tailor"the polyamide in many respects to produce a composition of the desiredproperties. Suitable cross linking agents are well known in the art andcan be used here in the conventional manner. Two compounds which we haveused include polyethyleneimine and tetra-(3-aminopropoxymethyl)methane.In addition, crosslinking can be achieved through the coupler byhydrolysis of silanol groups to form siloxane linkages,

by the use of polyfunctional promoters in a lactam polymerization, suchas diand triisocyanates or by the inclusion of polymers such aspolyisopropyl acrylamide or polymethyl methacrylate.

REINFORCING AGENTS The term filler as used herein refers to thosenonpolymerizable, discrete particles which are capable of existing andremaining in a discontinuous phase when placed in the presence of apolymer or polymerizing monomer and subjected to processing conditionsnecessary to shape the composite into a solid finished article.

lnorganic filler materials useful herein can be selected from a widevariety of minerals, metal oxides, metal salts such as metal aluminatesand metal silicates, other siliceous materials and mixtures thereof. Theterm reinforcing agent is used to designate filler materials which havebeen treated with a coupling agent to provide a capability for adherentbonding of filler to polyamide. To function as effective reinforcingagents under conditions of high moisture, it is imperative that thefiller materials be at most sparingly soluble in wa ter, not exceeding asolubility of about 0.15 gram per liter. lf, however, the finishedcomposition is to be used in an application where moisture sensitivityis not a problem, more soluble filler materials can be used. Generally,those hard, high modulus materials which have or can acquire an alkalinesurface upon treatment with a base are well suited for our reinforcedpolymeric compositions. By high modulus is meant a Youngs modulus ofelasticity at least twice as great as that of the base polyamide. Morepreferably, suitable inorganic fillers will have a Young's modulus of10' p.s.i. or greater. Many inorganics fulfill both preferredcharacteristics of high modulus and alkaline surface and thereforeconstitute one class of preferred filler materials. Since metalsilicates and siliceous materials usually have or can readily acquirethe desired alkaline surface, and since they are characterized bymodulus values well above the preferred minimum, a preferred mixture isone which contains a major amount, i.e. more than 50% by weight of metalsilicates or siliceous materials.

Materials with such characteristics are preferred because of the easewith which they are coupled to the polymer. However, other substancessuch as alumina, A1 0 which are not easily coupled to a polyamide bymeans of coupling agents employed herein, can nevertheless be used as areinforcing component either singly or preferably combined with otherminerals which are more susceptible to coupling, and more preferablycombined in minor amounts, i.e. percentages of less than 50% of thetotal reinforcing material. An example of such a material useful in theproduction of a reinforcing agent, with which alumina can be mixed, isfeldspar. Feldspar can be converted into one of the preferredreinforcing agents of this invention and a feldspar-alumina mixture isalso useful. Other materials particularly preferred for conversion intoreinforcing agents include wollastonite, which is a calciummetasilicate; mullite, an aluminum silicate; calcium magnesiumsilicates; and an acicular aluminum silicate, A1,. SiO Other usefulinorganics which can be converted into reinforcing agents include quartzand other forms of silica such as silica gel, carbon black, graphite,cristobalite, calcium carbonate, etc; metals such as aluminum, tin,lead, magnesium, calcium, strontium, barium, titanium, zirconium,vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc;metal oxides in general such as oxides of aluminum, tin, lead,magnesium, calcium, strontium, barium, titanium, zirconium, vanadium,chromium, manganese, iron, cobalt, nickel, copper, and zinc; heavy metalphosphates, sulfides, and sulfates, and basic mineral and mineral saltssuch as spodumene, mica, montmorillonite, kaolinite, bentonite,hectorite. beidellite, attapulgite, chrysolite, garnet, saponite andhercynite.

The term inorganic filler material or simply inorganic used in thisdisclosure refers to materials such as exemplified above. It should benoted that carbon black and graphite have been listed as suitableinorganic fillers. The term inorganic, in addition to conventionalinorganic materials, also includes those carbon-containing materialscharacterized by the substantial absence of carbon-hydrogen bonds, i.e.less than 1.5% by weight hydrogen. Particularly preferred are thoseinorganic siliceous materials which have a 3-dimensional crystalstructure as opposed to a 2-dimensional or planar crystal configuration.These siliceous materials are also characterized by a somewhatrefractory nature with a melting point above about 800C, a Mohs hardnessof at least 4, and a water solubility of less than 0.1 gram per liter.Examples of preferred siliceous materials include minerals such asfeldspar, quartz, wollastonite, mullite, kyanite, chrysolite,cristobalite, crocidolite, acicular aluminum silicate having the formulaAl,SiO,, spodumene and garnet. These minerals are especially desirablefor use in reinforced polyamide compositions for a number of reasons.For instance, they provide a composition with better abrasionresistance, flexural strength and modulus, tensile strength and modulus,impact resistance, resistance to heat distortion and resistance tothermal expansion than do conventional clay fillers and inorganicpigments such as whiting. F urther, the minerals described above providehigher loading levels than can be achieved with glass fibers, animportant economic consideration. In addition, highly loaded lactammonomer slurries can be directly cast into a final polymerized form,thereby eliminating several processing steps necessary with glassfiber-reinforced compositions.

Metals have been suggested above as suitable reinforcing agents. Inaddition to providing high strength,

reinforced polymeric compositions, the use of certain metals such ascopper, silver, iron and others can provide certain important auxiliaryadvantages. Moderate to high concentrations of metals can make thepolymeric composite electrically conductive, thereby rendering thecomposite suitable for an electroplating operation wherein the compositecan be electroplated with a thin coat of a metal such as chromium,silver, gold, etc. Or the use of iron or steel as a reinforcing agentcan give the polymeric composite magnetic properties if the particlesare oriented within the composition.

Inorganic filler materials useful herein are referred to as particulate.The term particulate as used in this disclosure refers to granular,plate-like and acicular particles having a length to diameter ratio l/d)up to about 25 to l. Preferably, the inorganics useful herein have anl/d ratio up to about 20 to l, and more preferably from about 1 to 1 upto about 15 to l. In contrast, the term fibrous refers to particleswhose l/d ratios are greater than 25 to l, and usually are greater than50 to I.

It is pointed out that plate-like particles. which can be considered asrods compressed in a direction parallel to their longitudinal axes, areconsidered herein to have l/d ratios of less than I to l. The plate-likefillers such as bentonite, kaolinite, talc and mica perform quitesatisfactorily when treated with a silane coupler and mixed with apreformed polyamide as described subsequently herein. Plate-likereinforcing agents also perform satisfactorily when placed in thepresence of diamine-dicarboxylic acid salts which are subsequentlypolymerized to form a polyamide. The use of plate-like reinforcingagents in polylactams provides only slight improvement, however, whenthe treated filler is placed in the presence of the lactam duringpolymerization. Perhaps this is due to the difficulty encountered inthoroughly drying such hydrated, high surface area minerals. Regardlessof the explanation, the plate-like tillers represent under thosecircumstances an important exception to the general reinforcingattributes of fillers of this invention.

Several characteristics of fillers have an effect on the maximumattainable loading of the composition. When the reinforced compositionis produced by casting a monomer-reinforcing agent mix directly into amold where the monomer is polymerized, the maximum content ofreinforcing agent is limited primarily by the viscosity of theumpolymerized mixture, i.e. too high a concentration of reinforcingagent produces mixtures too viscous to cast or mold. The limitationimposed by viscosity is in turn dependent to some extent upon the shapeof the particulate filler. That is, spherical particles do not increasethe viscosity of the monomer mix as much as highly acicular particles.By choosing particulate fillers of suitable shape, it is possible tomodify the viscosity of the monomer mix and prepare castable monomermixtures which can be used to produce polymeric compositions containinga very large amount of reinforcing agent.

Another factor which has an effect upon the upper limit of reinforcingagent concentration is the particle size distribution of the filler. Awide distribution of particle sizes provides a composition with a smallamount of voids or spaces between the particles, thereby requiring lesspolymer to fill these spaces and bind the particles together. Regardinggranular particle size. generally particles which pass through a 60 meshcreen (250 microns) are small enough to be used in he compositions ofthis invention although particles as arge as 1000 microns (18 mesh) ormore can be used vith equal or nearly equal success; with regard to aower limit on particle size, particles as small as 0.5;; lave beensuccessfully employed and smaller particles n the range of 100 to 200mg.can also be used. More .escriptive of suitable filler particles thanlimits on paricle size is a specification of particle size distribution.

\ suitable wide particle size distribution is as follows:

Percent 250p. or less (60 mesh) 100 l49p. or less (100 mesh) 90 44p. orless (325 mesh) 50 p. or less A narrower distribution also suitable foruse in this ivention is:

Percent 62p or less (230 mesh) lOO 44 or less (325 mesh) 90 l lp. orless 50 81.1. or less 10 A relatively coarse mixture useful in thisinvention as the following particle size distribution:

Percent 250p, or less (60 mesh) 100 i49 or less (I00 mesh) 90 lOSp. orless (140 mesh) 50 44;]. or less (325 mesh) 10 A finely-divided mixturehas the following particle lze distribution:

Percent 44p. or less (325 mesh) lOO ID or less 90 2,1. or less 50 0.5 orless l0 Other typical particle size distributions of reinforcingiinerals used in this invention include:

Wollastonite: Percent 74p. or less (200 mesh) 100 My. or less (325 mesh)99.7 1 lg. or less 50 in or less 8 Feldspar: Percent 50p. or less I0040p. or less 90 My. or less 50 10p. or less 38 3g. or less 10 'hesefigures regarding particle size distribution should or be construed aslimiting since both wider and nar- )wer ranges of distribution will alsobe useful as well 5 both coarser and finer compositions. Rather thesegures are intended as representative illustrations of ller compositionssuitable for use in the reinforced olymeric compositions of thisinvention.

Proper combination of the two variables of particle tape and particlesize distribution, together with a satfactory processing technique,permits the preparation f molded polymeric compositions containing asmuch 5 90% by volume or more reinforcing agent. The lower mit ofreinforcing agent concentration is restricted in- LII sofar as it isnecessary to have sufficient agent present to provide the extraordinaryimprovement in mechanical properties achieved by the compositions ofthis invention. The minimum level of reinforcing agent required toprovide compositions with properties significantly superior to prior artcompositions is about 25% by volume. The accompanying figure illustratesthe theoretical values of modulus predicted by the Einstein and by theKerner equations. Inspection of the figure indicates that at 20 volumepercent filler or slightly higher, the two theoretical equations predictsignificantly different modulus values. The reason for this departure isthat the Einstein equation is only reasonably accurate at low volumefractions of filler. Since considerations such as the relativemechanical properties of the two phases and the concentrations and sizeof the particulate filler, which become important as the quantity offiller is increased, are not considered in the Einstein equation, it isof little value in predicting modulus values of composites having morethan about 20 to 25 volume percent rigid dispersed filler. When theabove factors present in composites having high filler loadings areconsidered as in the Kerner equation, the theoretical moduli ofcomposites increases at a significantly different rate. Comparison ofthe two equations shows the above factors exert such an importantinfluence on composite containing more than 20 to 25% filler thatcomposites containing high filler loadings actually differ in kind fromcomposites containing lesser amounts. Also provided as points on thegraph are actual experimental results obtained on some of the reinforcedcompositions of this invention which show a rough adherence to the trendindicated by the Kerner equation.

Suitable values, therefore, for reinforcing agent concentration in thefinished compositions range from about 25 to about by volume of thetotal compositions. The above range corresponds approximately to about45 to about by weight using a filler density of 2.7 and a polymerdensity of 1.1. Filler concentrations are expressed herein in terms ofvolume percent since mechanical properties are more directly related tothe volume fraction of filler present as opposed to weight fractions. Apreferred range of filler concentration is from about 33 to about 67% byvolume or about 55 to about 84% by weight.

In addition, a small amount of fibrous material may be incorporated intoa polymer system if the amount of granular or acicular material isreduced by some pro' portionately larger amount. For example, 2 or 3% byvolume, based on the total reinforced composition, of glass fibers about0.5 inch in length can be incorporated into a monomer slurry containingabout 30 to 33% by volume granular feldspar. Similar quantities ofchopped asbestos fibers or other fibrous materials can also be used. Theresultant slurry can be cast about as readily as a monomer slurrycontaining 40% by volume granular feldspar. Alternatively, ifpourability is not required, larger amounts of fibrous material can beincluded in the composition, thereby reinforcing the final product to aneven greater extent.

COUPLING AGENTS An essential material in the preparation of ourreinforced polymeric compositions is the coupling agent which binds theinorganic filler to the polymer. Coupling agents useful herein are thosesubstituted silanes of the formula where X is a hydrolyzable groupcapable of reaction with a hydroxyl group, Y is a hydrogen or amonovalent hydrocarbon group, R is an alkylene group having from I toabout 20 carbon atoms, Z is a group capable of reaction with thepolyamide, n is an integer from to l, a is an integer from 1 to 3, b isan integer from 0 to 2, c is an integer from 1 to 3, and the sum ofa+b+cequals 4.

Examples of suitable X groups include halogen, hydroxy, alkoxy,cycloalkoxy, aryloxy, alkoxy-substituted alkoxy such as B-methoxyethoxy, alkoxycarbonyl, aryloxycarbonyl, alkyl carboxylate and arylcarboxylate groups, preferably having eight or less carbon atoms.Examples of Y groups in the above formula are hydrogen, methyl, ethyl,vinyl isobutyl and other hydrocarbyl groups, preferably having ten orless carbon atoms. The function of the Y grouup can be to modify theextent of the polymer-filler bond, to regulate viscosity of the monomerslurry or polymer mix or to modify the thermal stability of the coupler.The R group can be any a1- kylene group having up to about 20 carbonatoms and preferably from about 2 to about 18 carbon atoms; examplesinclude ethylene, propylene, decylene, undecylene, and octadecylene.Further, the R group need not necessarily be present at all as indicatedby the value of zero for the letter n. For instance, vinyl-substitutedsilanes are effective couplers. ln such an instance, the vinyl groupwhich is a Z group, is attached directly to the silicon atom. Usually,however, the Z group is separated from the silicon atom by an R grouphaving at least two carbon atoms in the linking chain. As the number ofcarbon atoms in the R group increases, the coupler can perform as avicosity reducer. Further, the activity of the Z group on the alkylenechain is often modified somewhat, thereby making the coupler performmore suitably under some processing conditions. The Z group can be anyfunctional group capable of reacting with a polyamide. Examples include,amino, primary or secondary amido, epoxy, isocyanato, hydroxyalkoxycarbonyl, aryloxycarbonyl, vinyl, allyl and halogen such as chloroand bromo groups.

It can be considered, as a working hypothesis, that chemical bonds areformed between polymer and coupler and between coupler and filler, butthis has not been conclusively established. But those couplers whichhave functional groups capable of such reactions provide compositionswith excellent properties whereas couplers not containing suchfunctional groups generally provide compositions with inferiorproperties. Adhesion of polymer to filler involves dual considerationsif the working hypothesis upon which this invention is based isaccurate. The first consideration is the polymer-coupler interface.Adhesion of polymer and coupler can be achieved under any conditionswhich permit thorough contact of the two components. One means has beento mix the coupler and filler with the polyamide-forming monomers andconduct a polymerization. Another means has been to mix thoroughly acoupler, filler and preformed polymer. Other techniques which providethe requisite contact of polymer and coupler can also be used. Reactioncan occur by several mechanisms such as aminolysis, alcoholysis, esterinterchange and alkylation. Aminolysis can occur by reaction of aminogroups or by amide interchangi with primary or secondary amido groupswith [ht amide groups of the polymer. Ester interchange car occur by thereaction of esters with the amide groups 0 the polymer. Alkylation canoccur by a reaction when an ethylenically unsaturated group reacts withthr amide group of the polymer. Alcoholysis can take place by thereaction of hydroxyl groups with an amide group. Additional reactions ofamide groups with othe1 functional groups are also known and can be userherein to provide the degree of adhesion of polymer tr filler whichforms the basis of the present invention. 1' should be noted inconnection with the above comments on polyamide-functional groupreaction that nei ther complete nor instantaneous reaction may benecessary. That is, if covalent bonding of polymer and coupler isresponsible for the extraordinary improvemenl achieved by the practiceof this invention, it is further theorized that only a fraction of thepossible polymer coupler bonds may provide as good or nearly as goodproperties in the finished compositions as would a complete reaction.The above hypothesis could explain why analytical characterization ofthe polymer-filler interface in terms of convalent or other types ofbonds is as yet beyond the skill of the art.

The second consideration regarding the adhesion ol polymer and filler isthe coupler-filler interface. Filler and coupler can be joined bycombining them in the absence or presence of a solvent for the coupler,such as water, alcohol, dioxane, benzene, etc. Presumably, thehydrolyzable group of the coupler reacts with appended hydroxyl groupsattached to the alkaline surface of inorganic materials. Theoretically,hydroxyl groups are present on the surface of, or can be developed onthe surface of, most metallic and siliceous substances, therebyproviding a site available for reaction with a hydrolyzable group of acoupler. This theory of availability of hydroxyl groups on an inorganicsurface may explain why many silicon-containing minerals are preferredreinforcing agents and why silicon-based coupling agents areparticularly preferred for use with the siliceous minerals, i.e. thesilane groups of the coupler-Si (OR)=,, react with the silanol groups ofthe inorganic,

to produce the very stable siloxane linkage,

l |SlO-?l= If the above theory is accurate, chemical bonding of couplerto the inorganic is achieved in the compositions of the presentinvention. Other theories can be advanced which deny the existence oftrue covalent bonds between inorganic and coupler. Regardless of anytheoretical explanation advanced herein, to which we do not intend to belimited, the coupler is attached to the inorganic by contacting the twosubstances. The mixture is preferably but not necessarily subsequentlydried. A bond between the inorganic and coupler is thus obtained. Thereaction of filler and coupler can be carried out separately, and thefiller-coupler adduct subsequently added to the monomer, or preformedpol- 1 1 ner, or the reaction may be carried out in the prestce of themonomer or polymer and the whole mix- |re dried to remove volatilereaction products and sol- :nts, if used. Preferably, heat in the rangeof 50 to )C or more is applied to a coupler-filler adduct to crease theextent of bonding.

l s s ls- 3 1 l-(trimethoxysilyl)undecyl SiC H B ethyl B-triethoxysilylpropionate, (C,H,O);,SiC,H

,COOC,H,;

methyl w-trimethoxysilylundecylate, (CH;,O);,.

SiC H COOCH glycidoxypropyl trimethoxysilane,

styrene.

chloride,

2 5 bromide,

(C11 0 ),SiC,H.OCH,CH CH,;

trimethoxysilyIethyl-3,4-epoxycyclohexane,

(CH,O),SiC,H,C.I-I,O; N-triethoxysilylpropyl amine, (C,H,0);SiC,H,NH,-,N-trimethoxysilylpro y1-N(B-aminoethyl]amine,

(CII OkSIC I'LN C,H,NH,; and N-trimethoxysilylundecyl (CH,C ),SiC1-I,,NH,. 1e amount of coupler with which the inorganic is :ated isrelatively small. As little as one gram of couing agent per 1000 gramsof filler produces a polyeric composition with mechanical propertiessuperior those of a polymeric composition containing an un- :atedfiller. Generally, quantities of coupler in the nge of 2.0 to 40.0 gramsper 1000 grams of reinforcg agent have been found most satisfactoryalthough lantities in excess of that range may also be used. Several ofthe compositions of this invention are aracterized by mechanicalproperties superior to re- :ed prior art compositions. As previouslymentioned, .e value helpful in screening suitable materials fromsuitable materials is the Strength Index. Generally, e higher theStrength Index of a composition, the are valuable it is for several ofthe uses mentioned ove. Strength Index is the product of the notched )dimpact strength and the square of the flexural *ength and is referred toherein by the abbreviated tation SI (strength impact). Compositionsparticu- 'ly preferred for several heavy-duty uses are those ving aStrength Index at least triple that of an equivaitly filled butuncoupled polyamide and a flexural )dulus at least double that of thecorresponding unled polyamide. Equivalent filling is obtained by using55 a same filler, same particle size, same concentration d same mannerof mixing with the same polymer max. For many preferred compositions,the Strength amine,

Index of the reinforced compositions will be six or eight times as greatas the Strength Index of the equivalently filled compositions and theflexural modulus will be at least triple that of the base resin.Numerical values will vary depending upon the particular polyamide underconsideration. The reinforced nylons such as polycaprolactam andpolyhexamethylene adipamide are characterized by Strength Index valuesof at leasat 40 X 10 ft. lbs.' in. together with flexural moduli of atleast 250,000 p.s.i. Preferable minimum levels for Strength Index andflexural modulus of reinforced nylon 6 and 6,6 are 50 X 10 and 300,000,respectively. Flexural strength and modulus are measured as described inASTM D-790. Izod notched impact strength is measured as described inASTM D-256, procedure A. The above measurements of properties are madeon moisture-equilibrated samples which have been boiled in water 72hours, cooled to room temperature and tested while wet.

PROCESS The compositions of this invention can be prepared bypolymerizing polyamide-forming monomers in the presence ofcoupler-treated fillers.

one technique used with considerable success in the practice of thisinvention has been to conduct a basecatalyzed, substantially anhydrouspolymerization of a lactam having a coupler-treated filler dispersedtherein. The filler can be treated with the coupler prior to itsaddition to the lactam monomer or the treatment can be achieved bymixing together filler, coupler, monomer and other optional additives.Base-catalyzed substantially anhydrous lactam polymerizations arecarried out by methods known to those skilled in the art usingappropriate catalysts, promoters, regulators, stabilizers, curingagents, etc. necessary to achieve the polymerization of a selectedlactam monomer. To prepare the compositions of this invention, it isnecessary to add to a lactam monomer, in addition to the abovecomponents, the coupler-treated filler. The polymerization isadvantageously carried out in a manner described in U.S. Pat. Nos.3,017,391, 3,017,392, 3,018,273 or 3,028,369 utilizing promoters,catalysts and regulators specified therein. One procedure suitable forpreparing reinforced polyamides comprises first mixing the lactammonomer, coupler, filler, water and if desired, a cross-linking agent,internal mold release agent, stabilizer or other additives. Mixing ismost effectively carried out if the lactam is in a molten condition.When high concentrations of reinforcing agent are used, e.g. 35 or 40%by volume or more, it may be advisable to add the components in theorder just given in order to effectively disperse the ingredients. Ifwater is used, it is advisable to use a small quantity, less than 10% ofthe total weight of the mixture, so that its complete removal from themixture is facilitated. About 1 to 5% water based on the weight of themixture is usually sufficient. After thorough mixing, the mixture isheated to about 1 10 C, but less than C, to remove any water and thehydrolyzed R groups of the coupler. A vacuum can be applied to aid inremoving the volatile materials. The temperature of the mixture is thenadjusted to some temperature above the melting point of the lactam,about 100C for s -caprolactam, and the polymerization catalyst is added.Any of the catalysts known to be acceptable for base-catalyzed lactampolymerizations are adequate; a preferred catalyst is an alkylmagnesiumhalide such as ethylmagnesium bromide.

Another preferred catalyst is sodium caprolactam. If a Grignard reagentis used, the temperature of the mixture is held around lC to permit thevolatilization of the alkane formed by reaction of the Grignard with thelactam monomer. Following addition of the catalyst and removal of alkaneif necessary, the promoter or initiator is added. Any of the promotersuseful in basecatalyzed lactam polymerizations can be used. Examplesinclude carbon monoxide; acyl caprolactams such as acetyl caprolactam;N,N-substituted carbodiimides such as diisopropylcarbodiimide anddicyclohexylcarbodiimide; and N,N-substituted cyanamides such asN,N-diphenyl cyanamide. Other suitable promoters include lactams havingattached to the imido group a heterocyclic substituent containing fromone to three heterocyclic atoms wherein at least one of the heterocyclicatoms is a nitrogen atom and wherein the imido group of the lactam isattached to a carbon atom in the heterocyclic ring so situtated that thenitrogen atom of the imido group and the nitrogen atom of theheterocyclic ring are connected by an odd number of conjugated carbonatoms. Examples of this class of promoters include: N-(2-pyridyl)- e-caprolactam; N-(4-pyridyl)-- e -caprolactam; tris-N-(2,4,6-triazino)--c -caprolactam; and N-(2-pyrazinyl)-- e -caprolactam. These promoterscan be formed by the in situ reaction of a lactam with such compounds asZ-chloropyridine, 4-bromopyridine, 2-bromopyrazine, Z-methoxypyridine,2-methoxypyrazine, 2,4,6-trichloro-s-triazine,2-bromo-4,6-dichloro-s-triazine, and 2,4-dimethoxy-6-chloro-s-triazine.A preferred class of promoters, namely organic isocyanates, is describedin detail in U.S. 3,028,369. Specific promoters preferred in our presentpolymerization include phenyl isocyanate, 2,4- and 2,6-tolylenediisocyanate, di-(p isocyanatophenyl) methane and a polyfunctionalisocyanate such as Mondur MR manufactured by Mobay Chemical Company.Alternately, the promoter may be added before the catalyst. Whicheverprocedure is followered, once the mixture contains the monomer,promotor, and catalyst, for most systems it is necessary to keep thetemperature below 140C, preferably below 120C, to prevent too rapidpolymerization until the mixture is cast. Some catalyst-promotersystems, such as the alkyl magnesium chloride-acetyl caprolactam system,will require even a further reduction in heat to less than 80C. toprevent polymerization. It is also advisable when employing a reactivecatalyst-promoter system to reduce the time intervening between theaddition of the catalyst-promoter and the casting or molding of themixture. After the mixture has been thoroughly stirred and allowed tocome to equilibrium, the mixture is cast into a mold, which ispreferably preheated, and polymerized at a temperature from about themelting point of the lactam up to about 250C, preferably from about 140to about 200C. Time for polymerization can vary from as little as oneminute or less up to an hour or more and usually requires from two orthree minutes up to about ten minutes with most preferredcatalyst-promoter systems. Other lengths of time and temperatures forpolymerization are of course satisfactory and can be used with equal ornearly equal success.

Selection of specific coupling agents can provide important benefits inthe preparation of reinforced polyamides by a base-catalyzed lactampolymerization process. For instance, U.S. Pat. No. 3,017,392 describesthe use of polymerization regulators in a base-catalyzed lactampolymerization. By choosing an aminosilane coupler such as3-triethoxysilylpropyl amine, the coupler can function as a polymeradherent, filler adherent and polymerization regulator simultaneously.In an alternate process, a compound such as N-phenyl, N-3-(triethoxysilyl) propyl urea can be used as a promoter as well as acoupler to achieve good adhesion of polymer to filler as well asinitiation of the lactam polymerization.

Not all coupling agents described herein as useful in preparingreinforced polyamides can be used successfully when the polyamide isprepared by a base-catalyzed anhydrous lactam polymerization in thepresence of coupler and filler. Again, theoretical conclusions areuncertain but experimental data indicate that for a compound to be aneffective coupler in a basecatalyzed lactam polymerization, it must notonly be capable of reaction with a polyamide but must further beincapable of a reaction with a monomeric lactam which will leave thesilane reaction product incapable of entering into the polymerization.For instance, ethylenically unsaturated silanes perform as satisfactorycouplers in a reinforced polyamide when the preformed polymer is mixedwith the coupler and filler, and the composition fabricated into afinished article. Similarly, the above couplers can be usedadvantageously in a condensation polymerization of a polyamine andpolycarboxylic acid. But the ethylenically unsaturated silane couplersare only marginally effective in a base-catalyzed lactam polymerization.Silane couplers where the Z group is a halogen atom are also onlymarginally effective. It is postulated that a reaction of monomericlactam and coupler such as the following occurs before polymerization;

a NH+CH,=CHSi NCH CH Si- (3 c o o The substituted monomeric lactamproduct, absent its active hydrogen atom, cannot enter into thepolymerization and the coupler cannot become bound to the polymer.Hence, preferred silane couplers useful in a lactam polymerization haveZ groups which are capable of reaction with a polyamide but incapable ofa reaction with a monomeric lactam which leaves the silane reactionproduct unable to enter the polymerization. Vinyl, allyl and halogensare examples of Z groups included by the broad definition of suitablecouplers but excluded by the above narrower class.

Regarding the preparation of castable compositions by the preferredmethod previously mentioned, it may be advisable, particularly in thecase of high loadings, of reinforcing agents where a slight increase inviscosity caused by partial polymerization cannot be tolerated, toprovide means for injection of the promoter (or alternately thecatalyst) into the monomer mixture as it is being poured or forced intothe mold. Such a technique completely prevents an increase in viscosityof the monomer mixture due to polymerization until the mixture is cast.Another technique useful with high loadings of reinforcing agents whichaids in overcoming the difficulties presented by high viscosity is apressurized injection of the monomer mixture into the mold. A techniquewhich we have found useful in decreasing the viscosity of monomerfiller-coupler slurries comprises adding a small amount of asurface-active agent to the slurry. Such a decrease in viscosity isadvantageous for two reasons. It permits the formation of a finer,smoother finish on the final product. Occasionally a finishedcomposition with a high reinforcing agent content, e.g. 60% by volume orabout 79% by weight filler, may have a granular or coarse texture andmay even contain voids or open spaces due to the inability of theviscous mixture to flow together completely prior to polymerization. Theaddition of a surt'ace-active agent eliminates this problem and produces1 smooth, attractive finish on highly reinforced compo- ;itions.Alternatively, if a smooth finish is not a neces- ;ary feature forcertain applications, then a decrease in tiscosity permits incorporationof larger amounts of renforcing mineral into the monomer mixture. Thissurace active agent may be either anionic, cationic, nononic or mixturesthereof. Examples include zinc stea- 'ate, dioctadecyl dimethyl ammoniumchloride, and :thylene oxide adducts of stearic acid. Preferred com-Jounds are the metal and quaternary ammonium salts )f long-chaincarboxylic acids. A concentration of suractant in the range of ODS-0.5%by weight of the total :ompositions has been found useful. However,lower :oncentrations may also be used. At higher concentraions ofsurface-active agent, it may be necessary to use idditional catalyst andpromoter.

In addition to the base-catalyzed, substantially anhylrous anioniclactam polymerization referred to above, 'einforced polyamides can alsobe prepared by the con- 'entional hydrolytic polymerization of lactamsin the iresence of coupler and filler as well as by polymerizaion ofaminocaproic acids.

Another process useful herein is the condensation iolymerization of apolyamine and polycarboxylic acid it the presence of coupler and filler.Preferably the mine and carboxylic acid are both difunctional. Examlesof amines include tetramethylene diamine, pentanethylene diamine,hexamethylene diamine, octanethylene diamine, dodecamethylene diamineand iis(paraamino cyclohexyl) methane. Suitable dicarioxylic acidsinclude adipic, pimelic, suberic, azelaic, ebacic, dodecanedioic andterephthalic acids. Amine alts of the acids are formed by reactingequivalent .mounts of the amine and acid in a suitable solvent for hesalt such as water or alcohol and recovering the alt. By way of example,the salt is dissolved in water to orm a to 75% aqueous solution. Afiller pretreated lith a silane coupler is added to the solution. Thereacor is then sealed and heated to about 200 to 240 C to levelop apressure of 250 p.s.i. After an hour or two, he temperature is raised to270 to 300C as steam is -led off to maintain the pressure at 250 p.s.i.The presure is then gradually reduced to atmospheric pressure ndadditional water removed. The polymer-coupleriller mixture can beextruded, chopped and molded to orm compositions having excellentmechanical proprties. Other methods of preparing reinforced polyamies bycondensation polymerization can also be emloyed using an inert solventfor the salt such as phenol, resol or xylenol and a non-solvent such asthe hydroarbons or chlorinated hydrocarbons optionally inluded.

Still another method of preparing reinforced polyamies comprises mixingtogether a polyamide, coupler nd filler under conditions which providethorough ontact of the filler-coupler adduct with the polyamide.

One method has been to place the three components in some container andagitate them to achieve some sort of crude dispersion. The dispersion isthen processed through an extruder, chopped into granules and injectionmolded. The filler can either be pre-treated with the coupler or treatedwith the coupler in the presence of the polymer. Another processingtechnique comprises milling the components followed by compressionmolding. Oxidative degradation of the polymer becomes a problem,however, unless care is taken to exclude air during the millingoperation. Other processing techniques are also applicable to thisinvention.

Polyamides prepared by any of the above processes can be reformed intogranules, pellets or powders and subsequently reworked if the degree ofcrosslinking in the polymer is minimized. One technique for reworkingcomprises extrusion followed by injection molding.

Such techniques, either singly or in combination with other techinquesknown in the art, are useful in obtaining the highly reinforcedcompositions of this invention.

The invention will be more clearly understood from the detaileddescription of the following specific examples which set forth some ofthe preferred compositions, the methods of preparing them, and thesuperior mechanical properties attained by the practice of thisinvention. Quantities of reinforcing agents are expressed in weightpercent.

EXAMPLE 1 A quantity of 300 grams (2.65 moles) of e-caprolactam wasmelted in a flask under an atmosphere of dry nitrogen. To this melt wasadded with stirring 750 grams of milled spodumene, a lithium aluminumsilicate. Following this, 3.5 ml. water and 6.4 grams (6.8 ml.) of3-aminopropyl triethoxysilane were also added. The mixture was heated to150C under a slight vacuum to remove water and ethanol. The distillationwas continued until 50 grams of caprolactam had also been removed. Thevacuum was released and the mixture allowed to cool to around I l5C, atwhich time 3.7 grams (3ml.) of an 80/20 mixture of 2,4- and 2,6-diisocyanatotoluene (TD-80) was added and mixed for several minutes. Tothis mixture, 8.3 ml. of a 3 molar solution of ethylmagnesium bromide indiethyl ether was added slowly with stirring. Again a vacuum was applieduntil all the ether and ethane were removed, as evidenced by thecomplete dispersal of the catalyst in the mixture. After release of thevacuum, the slurry was poured into a mold. preheated to 200C andpolymerized for one hour. The finished product contained 51% by volumewt. percent) spodumene.

Subsequent preparations patterned on this example use identicalquantities of all materials specified above unless otherwise noted.

EXAMPLE 2 The procedure described in Example I was followed except that750 grams of quartz with a wide particle size distribution wassubstituted in place of the spodumene. The finished product contained55% by volume (75 wt. percent) quartz.

EXAMPLE 3 The procedure described in Example 1 was followed except that750 grams of crystalline silica having a maximum particle size of 5p.and an average particle of 2p. was used instead of the spodumene. Thefinished product contained 55% by volume silica.

EXAMPLE 4 The procedure described in Example 1 was followed except that450 grams of e-caprolactam, 456 grams of wollastonite, a calciummetasilicate, 5.7 grams (4.7 ml.) of the difunctional isocyanate and13.3 ml. of a 3 molar solution of ethylmagnesium bromide in diethylether were used in place of the corresponding materials or quantitiesstated in Example 1. The finished product contained 32% by volume (53wt. percent) wollastonite.

EXAMPLE 5 The procedure described in Example 1 was followed except that350 grams of e-caprolactam, 700 grams of feldspar which is analuminum-alkali metal-alkaline earth metal silicate, 4.3 grams (3.5 ml.)of the difunctional isocyanate, and ml. of a 3 molar solution ofethylmagnesium bromide in diethyl ether were used in place of thecorresponding materials or quantities stated in Example 1. The finishedproduct contained 49% by volume (70 wt. percent) feldspar.

EXAMPLE 6 The procedure described in Example 1 was followed except that400 grams of e-caprolactam, 650 grams of wollastonite, 4.9 grams (4.0ml) of the difunctional isocyanate, and 10 ml. of a 3 molar solution ofethylmagnesium bromide dissolved in diethyl ether were used in place ofthe corresponding materials or quantities stated in Example 1. Thefinished product contained 43% by volume (65 wt. percent) wollastonite.

EXAMPLE 7 The procedure described in Example 1 was followed except that400 grams of e-caprolactam, 700 grams of mullite which is an aluminumsilicate, 6.8 grams (7.3 ml.) of 3-aminopropyl triethoxysilane, 3.7 mlwater, 4.3 grams (3.5 ml.) of the difunctional isocyanate and 10 ml. ofa 3 molar solution of ethylmagnesium bromide in diethyl ether were usedin place of the corresponding materials or quuantities stated in ExampleI. In addition, 100 grams of e-caprolactam was withdrawn by distillationinstead of 50 grams. The finished product contained 48% by volume (70wt. percent) mullite.

EXAMPLE 8 The procedure described in Example 1 was followed except that750 grams of mullite was used instead of spodumene. The finished productcontained 54% by volume (75 wt. percent) mullite.

EXAMPLE 9 the procedure described in Example 6 was followed. Inaddition, 1.25 grams of polyethylene imine was added as a crosslinkingagent.

EXAMPLE 10 The procedure described in Example 6 was followed except that3-(N-ethylamino)-aminopropyl trimethoxysilane was substituted in placeof the 3-aminopropyl triethoxysilane.

EXAMPLE 11 The procedure described in Example 6 was followed except that7 ml. water was used. in addition, 6.4 grams (6.8 ml.) of tetraethylsilicate was added.

EXAMPLE [2 The procedure described in Example 6 was followed inaddition, 6.4 grams of diphenylsilanediol was added EXAMPLE 13 Theprocedure described in Example 1 was follower except that 342 grams ofs-caprolactam, 650 grams 0' wollastonite, 58 grams of a chlorinatedterphenyl (62% Cl), 4.1 grams (3.4 ml.) of a difunctional isocyanate and8.8 ml. of a 3 molar solution of ethylmagnesiurr bromide in diethylether were added in place of the corresponding materials or quantitiesstated in Example 1 The finished product contained 43% by volume (65 wtpercent) wollastonite, 29.2% by weight polycaprolac tam, and 5.8% byweight of the chlorinated terphenyl EXAMPLE 14 The procedure describedin Example 1 was followed except that 750 grams of alumina was used inplace 01 the spodumene. The finished product contained 49% by volume wt.percent) alumina.

EXAMPLE 15 The procedure described in Example 6 was followed except that7.2 grams (6.0 ml.) of Mondur MR (a polyfunctional isocyanate) was usedas the promoter instead of the difunctional isocyanate of Example 1.

EXAMPLE l6 The procedure described in Example 6 was followed except that450 grams of e-caprolactam and 600 grams of wollastonite were used inplace of the corresponding quantities stated in Example 6. In addition,7.2 grams (6.0 ml) of Mondur MR was used as the promoter instead of thedifunctional isocyanate. Further, 1.25 grams of polyethylene imine wasadded as a crosslinking agent. The finished product contained 38% byvolume (60 wt. percent) wollastonite.

EXAMPLE 17 The procedure described in Example 1 was followed except that750 grams of enstatite which is a magnesium metasilicate was used inplace of the spodumene. The finished product contained 51% by volume (75wt. percent) enstatite.

EXAMPLE 18 A quantity of 350 grams (3.1 moles) of e-caprolactam wasmelted in a flask under an atmosphere of dry nitrogen. To this melt wasadded with stirring 6.4 grams (6.8 ml.) of 3-aminopropyltriethoxysilane, 650 grams of wollastonite, and 3.5 ml. water. Themixture was heated to 150C under a slight vacuum to remove water andethanol by-product. The distillation was continued until 50 grams ofcaprolactam had also been removed. The vacuum was released and themixture allowed to cool to around C, at which time 11.7 ml. of a 3 molarsolution of ethylmagnesium bromide in diethyl ether was added withstirring. A vacuum was applied until the catalyst was dispersed. Then amixture of 50 grams of caprolactam and 14.4 grams 12 ml.) of Mondur MRwas added. This mixture was prepared by mixing the two components,heating them to around C to cause their reaction, and distillingvolatile reaction products under a high vacuum. After addition of thereacted Mondur MR promoter, the mixture was stirred for 5 or 10 minutesunder a vacuum, then cast into a old preheated to 200C and allowed topolymerize for ie hour. The finished product contained 43% by volne (65wt. percent) wollastonite.

EXAMPLE 19 The procedure described in Example 18 was folwed except that28.8 grams (24 ml.) of Mondur MR IS used instead of the 14.4 grams (12ml.) stated in zample 18. In addition, 11 grams of tetra-(3-ymethyIene-l-propylamine)methane was added to e caprolactam beforemelting. This compound was (led as a crosslinking agent.

EXAMPLE 20 The procedure described in Example 18 was fol- .ved exceptthat 12.0 grams ml.) of the difunclnal isocyanate was used in place ofthe Mondur MR. addition, 1.0 gram of zinc stearate was added with 2catalyst and 2.6 grams of polyethyleneamine was ded with the promoter.The surface of the finished mposition had a smooth attractiveappearance.

EXAMPLE 21 A quantity of 300 grams (2.65 moles) of e-caprolacn wasmelted in a flask under an atmosphere of dry :rogen. To this melt wasadded with stirring l2.8 ams (13.6 ml.) of 3-aminopropyltriethoxysilane, 00 grams of mullite, and 7.0 ml. of water in the orderfen. The mixture was heated to 150C under a slight cuum to remove waterand hydrolyzed ethanol. This stillation was continued until 50 grams ofcaprolacn were removed. The mixture was allowed to cool to Jund 1 C,whereupon 2.0 grams of zinc stearate d 8.5 ml. of a 3 molar solution ofethylmagnesium omide in diethyl ether was added with stirring. A vacmwas applied to remove the ether and then 7.2 ims (6.0 ml) of Mondur MRwas added and stirred about 30 to 60 seconds. The slurry was cast intothe cheated mold, using a pressurized injection to insure mplete fillingof the mold, and polymerized at 200C one hour. The surface of thefinished composition d a grain-like, somewhat coarse texture but wasenely free from voids or open spaces large enough to versely affect thephysical properties. The finished oduct contained 68% by volume (86 wt.percent) illite.

EXAMPLE 22 A polymeric composition was prepared according to ample 6except that a finely-divided wollastonite was ad with a particle sizedistribution comparable to that :viously designated as suitable for afinely-divided xture. Additionally, a phenyl isocyanate promoter is usedin place of the difuctional isocyanate. In addin, 1.8 grams of zincstearate was added to the mono- :r slurry. The product was chopped intosmall pieces, need in a melt index device, heated to about 250C, dextruded through a l/16 inch orifice. The filament produced was thendrawn by hand to approximately 120 inch in diameter. The filamentsurface was ooth and possessed excellent physical properties.

The Table 1 below gives flexural strengths, flexural duli, and impactresistance values for polymeric mpositions of this invention. Theflexural strength d modulus values were determined in accordance th ASTMtest D 790-61. Impact resistance was deterned by the notched Izod impacttest described in ITM D 256-56. The numerical designations of polymericcompositions indicate compositions prepared as described in thecorresponding examples. Composition A is a unfilled, unreinforcedpolycaprolactam prepared according to Example 6 of this disclosureexcept that no reinforcing agent or coupling agent was used. CompositionB is a filled polycaprolactam containing 43% by volume wollastoniteprepared according to Example 6 of this disclosure except that nocoupling agent was used.

TABLE I Flexural Flexural Polymeric Strength, Modulus, Izod NotchedImpact Composition psi psi Resistance, ft. lbs/in.

A 12,000 030x10 0.80 B [9,740 1.55 0.71 1 23,500 2.34 0.86 2 19,600 2.160.64 3 25,200 2.6 0.58 4 20,200 1.36 0.91 5 24,700 1.82 0.87 6 27,9001.81 0.78 7 25,400 1.89 0.80 8 25,200 2.53 0.80 9 28,800 1.99 0.80 1023,500 1.73 0.72 11 25,700 1.61 0.58 12 25,800 1.75 0.82 13 22,000 1.570.74 14 24,900 2.53 0.66 15 30,200 2.09 0.80 16 22,700 1.34 1.00 1724,800 2.15 0.77 18 25,820 1.69 0.74 19 15,475 1.03 0.84 20 28,120 1.790.76

The above Table 1 demonstrates the great improvement in mechanicalproperties achieved by the reinforced polymeric compositions of thisinvention as compared to an unfilled, unreinforced polyamide and afilled but unreinforced polyamide. The flexural strength of unfilled,unreinforced polyamides has been more than doubled in some cases byreinforcement and has been increased by from 5% to more than 30% whencompared to merely filled polyamides. The modulus has been increasedapproximately by a factor of 6 to 8 when compared to the unfilled,unreinforced polyamide prepared in a comparable manner and by as much aswhen compared to the filled polyamide pre pared in a comparable manner.Additionally, impact resistance of 1 foot pound per inch has beenachieved with certain reinforcing media. The most accurate comparisonfor assessing the improvement achieved by the adherent bonding of thepresent invention vs. conventional filling is obtained by comparingSample B with Sample 6, the only difference in preparation being theinclusion of a coupling agent in Sample 6. It should be noted here thatnormal filling of a polyamide, although occasionally resulting inincreased flexural strength and modulus, also results in poorer impactresistance. However, this invention provides not only increased strengthand modulus but also increased impact resistance.

Sample 19 is an example of a highly crosslinked polyamide which can beprepared to satisfy certain particular requirements. Although theflexural strength and modulus of this composition is somewhat lower thansimilarly prepared uncrosslinked polyamides and the notched impactresistance is only average, the composition does not break duringflexural strength testing, but rather bends into a U-shape withoutfracturing. Further the impact resistance increases markedly when thesample is wet. The following is a comparison of Samples 15 and 19 whichare similar in all respects except as to the degree of crosslinking:

The inorganic mineral was contacted with 0.3% by weight of the silanecoupling agent and stirred for 30 minutes at 130C and for an additional20 minutes as EXAMPLES 23 to 38 The following runs were carried out todemonstrate the effects of different coupling agents upon reinforcedpolyamides prepared by the base-catalyzed, substantially anhydrousanionic polymerization of a lactam in the presence of a coupler-treatedfiller.

the mixture was cooled to 90 C. The treated mineral was added to moltene-caprolactam. To the monomermineral slurry was added l mmoles oftoluene diisocyanate per mole of caprolactam. A vacuum was then appliedfor minutes to remove volatile reaction products. To the resultantslurry either 7 millimoles of the magnesium catalyst or I l millimolesof the sodium polymerization catalyst per mole of caprolactam was addedand the mixture cast into a sheet mold :6 inch thick. The mold waspreheated to 200C and maintained at this temperature for ID minutesafter casting, after which time the mold was cooled and the polymerizedarticle removed. Properly data are reported in Table ll below. Alsoreported in the table are the type of filler, volume fraction of filler,type of silane coupler and catalyst system. One of two types of catalystwere used ethylmagnesium bromide or sodium caprolactam, which aredesignated in the table as Mg and Na. respectively.

TABLE ll DRY Composition Volume Flex. Str. Flex. Mod. Impact No. FillerFraction Coupler psi X l0 psi X l0 ft.lb./in.

23 wollastonite .42 (C,H,O),SiC,H,NH, 25.4 [.70 0.5 24 wollastonite .42(C,H,O),SiC,H,Nl-l, 24. 3 1.42 0.7 25 wollastonite .42 (C,H,O),SiC,H CNl I .5 0.95 0.2 26 wollastonite .42 (CH,O ),SiC H,,Br [4.7 1.l5 0.3 27wollastonite .42 c,ii,o ,sic,ii.ci [5.8 1.01 0.5 28 quartz .52(C,H,O),SiC,H.Cl 9.3 0.75 0.1

29 quartz .52 (CH,0),SiC,l-i [3:0 10.6 0.70 0.4

30 quartz .52 (c,H,o ,siC,H,NH. 12.4 0.71 0.5 31 wollastonite .42 (CH,OC,H.O),SiCH=CH, 14.7 L! 5 0.3 32 wollastonite .42 (CH,0),Si(Cl-l,) Nl-l,33 wollastonite .42 Cl,SiCl-l=CHCOOC.H 34 wollastonite .42Cl,Si(CH,)CH4IHCOOC.H,

CQOCDII3 i 45- 35 wollastonite .42 C 3 3 36 wollastonite .42CI,-Si(CH,)CH,CH(CHQCOOCH, 37 wollastonite .42 Cl,SiCH=CHCOOC,H, 38wollastonite .42 H,N(CH:)rC0NH(CH,);,Si(OMe),

WET Composition Volume Flex. Str. Flex. Mod. Impact No. Filler FractionCoupler psi X psi X 10 ft.lb./in. S'l

23 wollastonite .42 (C,H,O):SiC,H,NH 9.3 0.48 L0 87 24 wollasionite .42(C,H,O),SiC,H,NH, 6.8 0.35 2.3 I06 wollastonite .42 (C,l-l O) SiC,H CN5.0 0.36 0.8 20 26 wollastonite .42 (CH,O),SiC, H Br 4.9 0.27 0.9 22 27wollastonite .42 (C,H,O),SiC,H.Cl 5.3 0.34 0.7 20 28 quartz .52 c,i-i,o,s1c,ii.c1 3.5 0.35 1.4 17

29 quartz .52 (CH O),SiC,H @o 5.2 0.34 06 I6 quartz .52 (C,H,O),SiCH.NH, 6.4 0.36 1.9 78 3| wollastonite .42 (CH,OC,H.O),SiCH#IH, 4.9 0.270.9 22 32 wollastonite .42 (CH,0 Si(CH,),,Nl-l, 10.6 0.7l 80 33wollastonite .42 Cl,SiCH=CHCOOC l-l 10.9 0.44 52 34 wollastonite .42Cl,Si(CH,)CH=CHC0OC l-l, 10.9 LG l 19 C0001 ll t 't .42 (I l0.2 0.40 42we as out e TABLE lI-continued DRY 9 1* posmon Volume Flex. Str. Flex.Mod. Impact No. Flller Fraction Coupler psi X 10" psi X 10 ft.lb./in.

36 wollastonite .42 C1,Si(CH;,)CH,Cl- (CH,)COOCH, 10.0 0.71 71 37wollastonite .42 C| SiCH=CHCOC,H, 13.7 38 wollastonite .42H,N(CH,),CONH(CH,) Si(OMe);, 13.3

Inspection of the above data shows that silanes havng as their Z groupsa vinyl group or halogen atom are nferior to silane couplers whose 2groups are capable was chopped into a molding powder and injectionmolded at 260C and 600 p.s.i. Mechanical properties are reported toTable 111 below.

TABLE 111 DRY Composition Flex. Str. Flex. Mod. Ten. Str. Impact No.Coupler psi X psi X l0 psi X 10 ft.lb./in.

39 no coupler 17.6 1.33 9.1 0.4 40 (C,H OJ SIC H CN 17.6 1.67 10.5 0.241 (C,H,O),SiOC H 16.9 1.51 9.4 0.2 42 C1 SiCH; 13.0 1.47 7.6 0.1 43c,11,o ,s1c,11., 12.0 1.48 7.2 0.2

44 c,H.o ,s1 [9 13.7 1.64 7.8 0.2

45 (CJI O ),sic.11,c1 20.5 1.51 1 1.2 0.3 46 (CH,O);,SiCH#IH 19.7 1.3911.6 0.5 47 (C,H,,O);,SiCH=CH, 21.7 1.49 12.0 0.4

411 (CI-1,0),S1CJ1, 223 1.66 12.5 0.5

49 (C ,H,O) SiC;l-l.NH, 24.9 1.57 13.1 0.5 50 (CH;OC,H O),SiCH=CH 21.41.43 12.1 0.5 51 (c1-1,o),s1c,,11,,Br 22.0 1.02 12.3 0.4

WET

Com-

position Flex. Str. Flex. Mod. Ten. Str. Impact No. Coupler psi X 10 psiX l0" psi X 10* ft.Ib./in. S 1

39 no coupler 2.8 0.12 2.4 0.7 5 40 c,11,o1,s1c,11,cN 5.7 0.41 3.1 0.413 41 (C,H,O),SiOC H, 4.4 0.27 3.3 1.2 23 42 Cl,SiCl-l; 4.0 0.27 2.2(1.5) 24 43 (c,1-1.o),sic,11,, 4.4 0.3 2.3 (1.3) 25 44 c,11.o),s1- [Q4.8 0.33 2.4 (121* 2a 45 (C,H,O),SiC,H-Cl 8.3 0.39 4.6 0.7 48 46(CH,O);S1CH=CH, 8.0 0.39 4.9 0.8 51 47 (C,H,O),S1CH=CH g 8.7 0.38 5.20.8 61

4a cH,o ,sic,1-1, o 9.6 0.45 5.5 0.7 65

49 (C,H;O),S1C,H,NH, 9.4 0.39 5.3 0.8 71 50 (CH;,OC,H,O),SiCl-l=CI-l,9.5 0.36 5.2 0.8 72 51 CH,o),siC,,H,,Br 10.0 0.41 5.8 0.8 30

Samples did not break; calculated from scale reading.

f reacting in the manner described. Specifically, Comositions 23, 24,30, 32, 33, 34, 35, 36, 37 and 38 have iechanical propertiessignificantly superior to Compo- 1tions 25, 26, 27, 28, 29 and 31.

EXAMPLES 39 to 51 The following runs demonstrate the applicability of iepresent invention to reinforced polyamides preared by dispersing thecoupler-treated filler in the pre- )rmed polyamide.

Nylon 6,6 (Zytel 101) molding powder was placed in polyethylene bag towhich was added sufficient wolistonite to provide a finished compositionhaving 0.42 olume fraction filler (65% by wt.) and alkoxysilane ouplerequal to 1% by weight of the filler. The con- :nts of the bag wereagitated for about 30 to 60 secnds and then placed in an extruder havinga 1 inch :rew and 18 inch barrel length. The contents were run troughthe extruder twice at 270 C. The extrudate Inspection of the above dataof Table 111 indicates the importance of a silane coupler containing afunctional group capable of reacting with a polyamide. Compositionsimproperly coupled because of unreactive Z groups on the coupler, Nos.40 to 44 in the above table, are somewhat improved over a merely fillednylon but the choice of proper silane coupler, as in Nos. 48 to 51,provides at least as much additional improvement of the properly coupledcompositions over the improperly coupled compositions in the importantStrength Index category as is shown by the improperly coupled materialsover the filled material of Example 39.

EXAMPLES 52 to 55 The following runs were carried out as described inthe procedure for Examples 39 to 51 except that the type of filler wasvaried as indicated in Table IV below.

TABLE IV DRY Composition Flex.Str. Flex.Mod. Ten.Str. lmpact No. MineralCoupler psi X lpsi X 10 psi X 10 ft.1b./in

52 feldspar (CH OhsiC H Nl-l, 21.4 1.25 1 1.2 0.4 53 quartz (CH OhsiC flNH, 20.9 1.12 10.8 0.4 49 wollastonite (Cl-1,0 );,SiC,l-l,NH, 24.9 1.5713 .1 0.5 54 feldspar (C,H,O),SiC,H,Cl 21.7 1.28 1 1.7 0.4 55 quartz(C,H,O) -,SiC,H,Cl 21.6 1.35 l 1.8 0.4 45 wollastonite (C,H .,O)SiC,H,Cl 20.5 1.51 1 1.2 0.3

WET Composition Flex.Str. Flex.Mod. Ten.Str. Impact No. Mineral Couplerpsi X 10 psi X 10 psi X 10 ft.lb./in. S 1

52 feldpsar (CH O),SiC;I-1,NH, 10.5 0.41 6.5 0.9 99 53 quartz(Cl-l,O),,SiC H,NH, 8.6 0.32 5.6 0.8 59 49 wollastonite (Cl-l,O) SiCH.NH, 9.4 0.39 5.3 0.8 71 54 feldspar (C,H,O),SiC,H,Cl 10.0 0.40 5.7 0.880 S quartz (C,l-l,,0),SiC,l-*1,Cl 9.8 0.40 5.8 0.8 78 45 wollastonite(C,l-l,O),SiC;l-l,Cl 8.3 0.39 4.6 0.7 48

The above data of Table IV indicate the specificity of differentcoupler-filler adducts with polyamides and the variation in propertiesobtained using different couplers with different fillers in the resin.Compare for inture was cured in a press for two hours at 85C and subsequently post cured in an oven for 20 hours at 135C Thepolycaprolactams were prepared according U the procedure followed forExample 1.

TABLE V DRY Vol. Frac. Flex.Str. Flex.Mod. lmpact Composition No. ResinFiller Coupler psi X psi X 10" 1't.lb./in.

56 polyester none none 14.1 .55 0.2 57 polyester .57 none 9.6 2.7 01 58polyster .57 CH,=C(CH;,)C(O)O 18.8 4.0 0.l

(CH,O),SiH,C 59 epoxy none none 7.9 .30 60 epoxy .47 none 8.9 1.8 61epoxy .47 (C,H -,O) -,SiC H,Nl-l, 10.2 1.8 62 polycapronone none 1 2.00.3 0.80

lactam 63 polycapro- .49 none 16.0 1.9 0.50

lactam 64 polycapro- .49 (C,H,O 27.1 2 .2 0.50

lactam stance Compositions 52 and 53 with 49 and Compositions 54 and 55with 45.

EXAMPLES 56 to 64 The following data reported in Table V belowdemonstrate that various resins perform in different manners whensubjected to the action of a reinforcing filler.

The polyester compositions were prepared by mixing Paraplex P-43 (a70/30 mix of an unsaturated polyester in styrene) with wollastonite,0.5% by weight based on the mineral of 3-trimethoxysilylpropylmethacrylate and benzoyl peroxide catalyst in a Banbury mixer for 10minutes. The dough-like mix was molded and polymerized for 5 minutes at110C and 300 p.s.i. The product was then cured for hours at 1 10C. Thefinished product contained 55% by volume (75 wt. percent) wollastonite.

The epoxy compositions were prepared by mixing 140 parts of wollastonitewith 4 parts of 3-trimethoxysilylpropylamine and parts of an epoxyprepolymer (Oxiron 200). To the mix was added 20 parts of a 7/1 blend ofmaleic anhydride/propylene glycol. The mixlnspection of the above datashows that the impac' strength of filled and of reinforced polyesters isadversely affected. As a matter of fact, the impact strength is reducedvirtually to zero. The flcxura strength of a reinforced polyester isimproved aboul 26% by comparison to the base resin. Granularreinforcement of an epoxy resin has little effect on the flex uralproperties; no impact data is available for comparison. Polyamides, onthe other hand, show remarkable improvement in flexural strength, 1 13%over the base resin, as well as good retention of impact strength Hence,the specific nature of polymer systems has considerable effect upon itscapability or respond to granular reinforcement.

EXAMPLES 65 and 66 The procedure described for Examples 39 to 51 wasused. Instead of wollastonite. a plate-like filler, mica was used at aloading of 28% by volume (52 wt. per cent). The composition of Example65 did not contain a coupler. in Example 66, 1% by weight based on thefiller of 3-trimethoxysilylpropyl amine was used. Results are reportedin Table VI.

TABLE VI DRY npo- Flex. Str. Flex. Mod. Tens. Str. Impact ion Couplerpsi X psi X 10 psi X 10 Strength 65 no 192 1.5 10.1 0.3 66 yes 21.5 1.512.| 0.4

WET

npo- Flex. Str. Flex. Mod. Tens. Str. Impact ion psi X 10' psi X 10 psiX 10* Strength 5 1 erable detail, it should be understood that this wasdone EXAMPLE 67 IS for illustrative purposes only, and that theinvention is quantity of 500 parts of feldspar (average particle notnecessarily limited thereto since alternative em- 25p) was mixed with 5parts of ll-trimethoxbodiments and operating techniques will becomeaplylundecyl bromide and 50 parts ofa nylon 6,6 moldparent to thoseskilled in the art in view of this disclopowder (Zytel 101 The mixturewas extruded and sure. For instance, it is possible to fill thesecomposiection molded as described above in Examples 39 to tions with afiller, i.e. with additional inorganic particu- The finished product wasmolded into a cylindrical late material which is not coupler-treated asis the reinipe 1.25 inches in diameter. The cylinder was forcing agent.As an example, a mold may be loosely ooth, hard, strong and of excellentuniform appearfilled with a mixture of large (approximately 1 cm. in ce.The article contained 80% by volume (91 wt. diameter) irregular mineralparticles and sand, and a rcent) feldspar. monomer-coupler-filler slurryas described in the pre ceding examples may be poured into the mold,thereby EXAMPLES 68 to 76 wetting the large particles in the mold andfilling the [he accompanying figure shows the modulus values spacesbetween the particles before polymerization ocdifferent filler loadingsfor some of the compositions curs. In such a case, the reinforcedpolymer binds the this invention. sand and larger aggregates together inmuch the same The quartz-loaded nylon 6,6 compositions were preway ascement binds sand gravel together to form a fin red as described inExamples 39 to 51 using 1% 3- ished concrete. As an alternate method,the inorganic ethoxysilylpropyl amine on the quartz. aggregate in themold may be treated with a suitable The wollastonite-loaded andquartz-loaded polycapcoupling agent prior to the introduction of themonomlactams were prepared as described in Examples 23 er-coupler-fillerslurry so that upon casting, the entire 38 using the sodium caprolactamcatalyst. Table Vll mixture is adherently bound to the polymer, therebylow sets forth the properties of the reinforced comproducing areinforced composition wherein the reinsitions. forcing medium mayexceed 90% by volume of the TABLE Vll mpo- Vol. F1ex.Str. Flex.Mod.Impact tion Polymer Frac. Filler psi X 10 psi X 10" ft.1b./in.

68 nylon 6,6 .15 quartz 24.2 0.53 0.5 69 nylon 6,6 .20 quartz 16.7 0.410.4 70 nylon 6,6 .30 quartz 20.1 0.78 0.5 71 nylon 6 .42 quartz 23.81.50 0.6 72 nylon 6 .50 quartz 24.2 1.78 0.5 73 nylon 6 .52 quartz 25.21.92 0.5 74 nylon 6 .62 quartz 2.66 0.4 75 nylon 6 .15 wollastonite 1600.53 0.5 76 nylon 6 .45 wollastonite 25.4 1.70 0.5

The improved properties of the reinforced polyamtotal composition.Similarly, glass fibers in the form of as permit their use in manyapplications in which the mats or woven cloth can be impregnated withthe parlreinforced polyamides are unsuitable, such as the ticulatelyreinforced compositions of this invention to brication of tables,chairs, drawers, and other furni produce articles having a very highinorganic content. re and furniture components, heavy duty equipmentAccordingly, these and other modifications are coniusings, automobilecomponents and building contemplated which can be made without departingfrom ruction components. The reinforced filaments are the spirit of thedescribed invention. eful in the manufacture of tire bodies. They canalso What is claimed is: used as an oriented reinforcing material inother 1. A reinforced polymeric composition comprising a impositions toimprove impact resistance and polyamide and at least about 25% by volumeof an inorrength. Further, the compositions of this invention ganicfiller material having a length to diameter ratio of e generally usefulin those applications in which unreup to about 25 to 1, said materialhaving been treated forced polyamides have been useful but where inwithan organosilane coupling agent of the formula eased strength, rigidity,and impact resistance are derable features.

Although the invention has been described in terms specified embodimentswhich are set forth in considwhere X is a hydrolyzable group capable ofreaction with a hydroxyl group, Y is hydrogen or a monovalenthydrocarbon group, R is an alkylene group having from I to about 20carbon atoms, Z is a group capable of reaction with a polyamide, n is aninteger from to l, a is an integer from I to 3, b is an integer from 0to 2, c is an integer from 1 to 3 and the sum of a-i-b+c equals 4.

2. A reinforced polymeric composition according to claim 1 wherein saidpolyamide is a polylactam.

3. A reinforced polymeric composition according to claim 1 wherein saidpolyamide is a polylactam whose monomeric units contained at least sixcarbon atoms.

4. A reinforced polymeric composition according to claim 1 wherein saidpolyamide is polycaprolactam.

S. A reinforced polymeric composition according to claim I wherein siadpolyamide is a condensation product of a polyamine and polycarboxylicacid.

6. A reinforced polymeric composition according to claim 1 wherein saidpolyamide is polyhexamethylene adipamide.

7. A reinforced polymeric composition according to claim 1 wherein saidfiller comprises from about 25 to about 90% by volume of the totalcomposition.

8. A reinforced polymeric composition according to claim 1 wherein saidfiller comprises from about 33 to about 67% by volume of the totalcomposition.

9. A reinforced polymeric composition according to claim 1 wherein saidfiller is an inorganic siliceous ma terial which has a 3-dimensionalcrystal structure, a somewhat refractory nature with a melting pointabove about 800C, a Mohs hardness of at least 4, and a water solubilityof less than 0.1 gram per liter.

10. A reinforced polymeric composition according to claim 1 wherein saidfiller is a plate-like filler with a length to diameter ratio of lessthan 1 to l.

l l. A reinforced polymeric composition according to claim 1 whereinsaid filler has a length to diameter ratio from about l to 1 up to about20 to 1.

12. A reinforced polymeric composition according to claim 1 wherein saidcoupling agent has the formula where X is halogen or alkoxy, R is analkylene group having from about 2 to about 18 carbon atoms, Z is amino,secondary amido, isocyanato, halogen, alkoxycarbonyl, epoxy, vinyl,acryloxy, or methacryloxy, and n is 0 or 1, provided that n can be zeroonly when 2 is a vinyl group.

13. A reinforced polymeric composition according to claim 1 wherein saidcoupling agent is 3-trialkoxysilylpropyl amine.

14. A reinforced polymeric composition according to claim 1 wherein saidcoupling agent is ll-(trialkoxysilyl)-undecyl bromide.

15. A reinforced polymeric composition according to claim 1 wherein saidcoupling agent is tri(B-methoxyethoxy)vinyl silane.

16. A reinforced polymeric composition according to claim 1 wherein saidcoupling agent is 3-(trialkoxysilyl)propyl chloride.

17. A reinforced polymeric composition according to claim 1 wherein saidcomposition is characterized by a Strength Index at least triple that ofan equivalently filled but uncoupled composition and a flexural modulusat least double that of the base resin.

18. A reinforced polymeric composition according to claim 1 wherein saidpolyamide is polycaprolactam or polyhexamethylene adipamide and whereinsaid composition is characterized by a Strength Index of at least 40 X10 and a flexural modulus of at least 250,000 psi.

19. A reinforced polymeric composition comprising a polyamide and fromabout 33 to about 67% by volume of an inorganic siliceous fillermaterial which has a 3-dimensional crystal structure, a somewhat refractory nature with a melting point above about 800C, a Mohs hardness of atleast 4, a water solubility of less than 0.1 gram per liter and a lengthto diameter ratio from about 1 to 1 up to about 20 to 1, said fillermaterial having been treated with an organosilane coupling agent of theformula where X is halogen or alkoxy, R is an alkylene group having fromabout 2 to about 18 carbon atoms, 2 is amino, secondary amido,isocyanato, halogen, alkoxycarbonyl, cyclohexylepoxy, epoxy, vinylacryloxy, or methacryloxy, and n is 0 to 1, provided that n can be zeroonly when 2 is a vinyl group, said reinforced polymeric compositionbeing characterized by a Strength index at least triple that of anequivalently filled but uncoupled composition and a flexural modulus atleast double that of the base resin.

20. A reinforced polymeric composition according to claim 19 whereinsaid polyamide is polycaprolactam or polyhexamethylene adipamide andwherein said composition is characterized by a Strength Index of atleast 40 X 10 and a flexural modulus of at least 250,000.

21. A process for preparing a filler-reinforced polyamide compositionhaving at least 25% by volume filler comprising (a) treating aninorganic filler material having a length to diameter ratio of at leastI to 1 up to about 25 to l with an organosilane coupling agent of theformula where X is a hydrolyzable group capable of reaction with ahydroxyl group, Y is hydrogen or a monovalent hydrocarbon group, R is analkylene group having from 1 to about 20 carbon atoms, Z is a groupcapable of reaction with a polyamide but incapable of a reaction with amonomeric lactam which leaves the resultant silane-lactam adductincapable of entering into a polymerization, n is an integer from 0 tol, a is an integer from 1 to 3, b is an integer from 0 to 2, c is aninteger from 1 to 3, and the sum of a+b+c equals 4 and (b) conducting abase-catalyzed, substantially anhydrous, anionic polymerization of alactam in the presence of said filler and said coupler.

22. A process according to claim 21 wherein said filler is treated withsaid coupler prior to its addition to the monomer.

23. A process according to claim 21 wherein the monomer which ispolymerized is e -caprolactam.

24. A process according to claim 21 wherein the 2 group of saidorganosilane coupling agent is an amino group having at least onehydrogen atom, which amino 31 group functions as a polymerizationregulator.

25. A process according to claim 21 wherein said organosilane couplingagent has the fomiula where R is an alkyl group and R is an alkylenegroup having from about 2 to 18 carbon atoms.

26. A process according to claim 21 wherein said organosilane couplingagent is 3-( triethoxysilyl)propyl amine.

27. A process according to claim 21 wherein the Z group of saidorganosilane coupling agent contains a nitrogen atom capable offunctioning as a polymerization promoter.

28. A process according to claim 21 wherein said organosilane couplingagent is N-phenyl, N'-3-(triethox ysilyl)propyl urea.

29. A process according to claim 21 wherein the promoter is apolyfunctional isocyanate.

30. A process according to claim 21 wherein the catalyst is analkylmagnesium halide.

31. A process according to claim 21 wherein the catalyst is sodiumcaprolactam.

32. A process according to claim 21 wherein said filler is an inorganicsiliceous material having a length to diameter ratio of from about l toI up to about 25 to l, a three-dimensional crystal structure, a somewhatrefractory nature with a melting point above about 800C, a Mohs hardnessof at least 4, and a water solubility of less than 0.1 gram per liter.

33. A process for preparing a filler-reinforced polyamide compositionhaving at least 25% by volume filler comprising (a) adding to amonomeric lactam, an inorganic siliceous filler having a length todiameter ratio of at least up to about 25 to l, a somewhat refractorynature with a melting point above about 800C, a Mohs hardness of atleast 4, and a water solubility of less than 0.1 gram per liter, anorganosilane coupling agent of the formula where R is an alkyl group andR is an alkylene group having from about 2 to 18 carbon atoms, and alactam polymerization promoter,

(b) removing volatile reaction products if any,

(c) holding the umpolymerized mixture for an indefinite period of time.

(d) adding a lactam polymerization catalyst,

(e) casing the resultant mixture into a mold, and

(f) maintaining the mixture at a temperture and for a time sufficient toachieve polymerization.

34. A reinforced polyamide article comprising a polyamide and at least25% by volume of an inorganic filler material having a length todiameter ratio of up to about 25 to l and a water solubility of lessthan 0.15 grams per liter, said material having been treated with anorganosilane coupling agent of the formula where X is a hydrolyzablegroup capable of reaction with a hydroxyl group, Y is hydrogen or amonovalent hydrocarbon group, R is an alkylene group having up to about20 carbon atoms, Z is a group capable of reac- 32 tion with a polyamide,n is an integer from 0 to l, a is an integer from I to 3, b is aninteger from O to 2, c is an integer from I to 3 and the sum of a+b+cequals 4.

35. A reinforced polyamide article according to claim 34, said articlecharacterized by a Strength Index at least triple that of anequivalently filled but uncoupled article and a flexural modulus atleast double that of an unfilled article made from the base polyamideresm.

36. A reinforced polymeric composition according to claim 17 whereinsaid polyamide is a polylactam.

37. A reinforced polymeric composition according to claim 17 whereinsaid polyamide is a condensation product of a polyamine and apolycarboxylic acid.

38. A reinforced polymeric composition according to claim 1 wherein saidfiller is a crystalline silica having a maximum particle size of about 5microns and an average particle size of about 2 microns.

39. A reinforced polymeric composition according to claim 1 wherein saidcoupling agent has the formula where X is halogen or alkoxy, R is analkylene group having from about 2 to 18 carbon atoms, and Z is amino,secondary amido, isocyanato, alkoxycarbonyl or epoxy.

40. A reinforced polymeric composition comprising a polyamide and fromabout 33 to 67% by volume of an inorganic siliceous filler materialwhich is characterized by a 3-dimensional crystal structure, a somewhatrefractory nature with a melting point above about 800C, a Mohs hardnessof at least 4, a water solubility of less than about 0.1 gram per literand a length to diameter ratio from about 1:1 up to about 20:1, saidfiller material having been treated with an organosilane coupling agentof the formula where X is halogen or alkoxy, R is an alkylene grouphaving from about 2 to 18 carbon atoms, and Z is amino, secondary amido,isocyanato, alkoxycarbonyl or epoxy, said reinforced polymericcomposition being characterized by a Strength Index at least triple thatof an equivalently filled but uncoupled composition and a flexuralmodulus at least double that of the base resin.

41. A reinforced polymeric composition according to claim I wherein saidfiller has a Mohs hardness of at least 4.

42. A reinforced polymeric composition according to claim 41 whereinsaid filler has been treated with an organosilane coupling agent havingthe formula Xa-Si-R -z where X is alkoxy having up to 8 carbon atoms, Ris an alkylene group having from about 2 to about 18 carbon atoms and Zis amino.

43. A reinforced polymeric composition according to claim 42 whereinsaid coupling agent is 3-triethoxysilylpropyl amine.

44. A reinforced polymeric composition according to claim 43 wherein thepolyamide is polycaprolactam.

45. A reinforced polymeric composition according to claim 43 wherein thepolyamide is polyhexamethylene adipamide.

1. A REINFORCED POLYMERIC COMPOSITION COMPRISING A AMIDE AND AT LEASTABOUT 25% BY VOLUME OF AN INORGANIC FILLER MATERIAL HAVING A LENGTH TODIAMETER RATIO OF UP TO ABOUT 25 TO 1, SAID MATERIAL HAVING BEEN TREATEDWITH AN ORGANOSILANE COUPLING AGENT OF THE FORMULA
 2. A reinforcedpolymeric composition according to claim 1 wherein said polyamide is apolylactam.
 3. A reinforced polymeric composition according to claim 1wherein said polyamide is a polylactam whose monomeric units containedat least six carbon atoms.
 4. A reinforced polymeric compositionaccording to claim 1 wherein said polyamide is polycaprolactam.
 5. Areinforced polymeric composition according to claim 1 wherein siadpolyamide is a condensation product of a polyamine and polycarboxylicacid.
 6. A reinforced polymeric composition according to claim 1 whereinsaid polyamide is polyhexamethylene adipamide.
 7. A reinforced polymericcomposition according to claim 1 wherein said filler comprises fromabout 25 to about 90% by volume of the total composition.
 8. Areinforced polymeric composition according to claim 1 wherein saidfiller comprises from about 33 to about 67% by volume of the totalcomposition.
 9. A reinforced polymeric composition according to claim 1wherein said filler is an inorganic siliceous material which has a3-dimensional crystal structure, a somewhat refractory nature with amelting point above about 800*C, a Mohs'' hardness of at least 4, and awater solubility of less than 0.1 gram per liter.
 10. A reinforcedpolymeric composition according to claim 1 wherein said filler is aplate-like filler with a length to diameter ratio of less than 1 to 1.11. A reinforced polymeric composition according to claim 1 wherein saidfiller has a length to diameter ratio from about 1 to 1 up to about 20to
 1. 12. A reinforced polymeric composition according to claim 1wherein said coupling agent has the formula X3-Si-RnZ where X is halogenor alkoxy, R is an alkylene group having from about 2 to about 18 carbonatoms, Z is amino, secondary amido, isocyanato, halogen, alkoxycarbonyl,epoxy, vinyl, acryloxy, or methacryloxy, and n is 0 or 1, provided thatn can be zero only when Z is a vinyl group.
 13. A reinforced polymericcomposition according to claim 1 wherein said coupling agent is3-trialkoxysilylpropyl amine.
 14. A reinforced polymeric compositionaccording to claim 1 wherein said coupling agent is11-(trialkoxysilyl)-undecyl bromide.
 15. A reinforced polymericcomposition according to claim 1 wherein said coupling agent is tri(Beta -methoxyethoxy)vinyl silane.
 16. A reinforced polymeric compositionaccording to claim 1 wherein said coupling agent is3-(trialkoxysilyl)propyl chloride.
 17. A reinforced polymericcomposition according to claim 1 wherein said composition ischaracterized by a Strength Index at least triple that of anequivalently filled but uncoupled composition and a flexural modulus atleast double that of the base resin.
 18. A reinforced polymericcomposition according to claim 1 wherein said polyamide ispolycaprolactam or polyhexamethylene adipamide and wherein saidcomposition is characterized by a Strength Index of at least 40 X 106and a flexural modulus of at least 250,000 p.s.i.
 19. A reinforcedpolymeric composition comprising a polyamide and from about 33 to about67% by volume of an inorganic siliceous filler material which has a3-dimensional crystal structure, a somewhat refractory nature with amelting point above about 800*C, a Mohs'' hardness of at least 4, awater solubility of less than 0.1 gram per liter and a length todiameter ratio from about 1 to 1 up to about 20 to 1, said fillermaterial having been treated with an organosilane coupling agent of theformula X3-Si-RnZ where X is halogen or alkoxy, R is an alkylene grouphaving from about 2 to about 18 carbon atoms, Z is amino, secondaryamido, isocyanato, halogen, alkoxycarbonyl, cyclohexylepoxy, epoxy,vinyl acryloxy, or methacryloxy, and n is 0 to 1, provided that n can bezero only when Z is a vinyl group, said reinforced polymeric compositionbeing characterized by a Strength Index at least triple that of anequivalently filled but uncoupled composition and a flexural modulus atleast double that of the base resin.
 20. A reinforced polymericcomposition according to claim 19 wherein said polyamide ispolycaprolactam or polyhexamethylene adipamide and wherein saidcomposition is characterized by a Strength Index of at least 40 X 106and a flexural modulus of at least 250,000.
 21. A process for preparinga filler-reinforced polyamide composition having at least 25% by volumefiller comprising (a) treating an inorganic filler material having alength to diameter ratio of at least 1 to 1 up to about 25 to 1 with anorganosilane coupling agent of the formula
 22. A process according toclaim 21 wherein said filler is treated with said coupler prior to itsaddition to the monomer.
 23. A process according to claim 21 wherein themonomer which is polymerized is epsilon -caprolactam.
 24. A processaccording to claim 21 wherein the Z group of said organosilane couplingagent is an amino group having at least one hydrogen atom, which aminogroup functions as a polymerization regulator.
 25. A process accordingto claim 21 wherein said organosilane coupling agent has the formula(R1O)3Si-R-NH2 where R1 is an alkyl group and R is an alkylene grouphaving from about 2 to 18 carbon atoms.
 26. A process according to claim21 wherein said organosilane coupling agent is 3-(triethoxysilyl)propylamine.
 27. A process according to claim 21 wherein the Z group of saidorganosilane coupling agent contains a nitrogen atom capable offunctioning as a polymerization promoter.
 28. A process according toclaim 21 wherein said organosilane coupling agent is N-phenyl,N''-3-(triethoxysilyl)propyl urea.
 29. A process according to claim 21wherein the promoter is a polyfunctional isocyanate.
 30. A processaccording to claim 21 wherein the catalyst is an alkylmagnesium halide.31. A process according to claim 21 wherein the catalyst is sodiumcaprolactam.
 32. A process according to claim 21 wherein said filler isan inorganic siliceous material having a length to diameter ratio offrom about 1 to 1 up to about 25 to 1, a three-dimensional crystalstructure, a somewhat refractory nature with a melting point above about800*C, a Mohs'' hardness of at least 4, and a water solubility of lessthan 0.1 gram per liter.
 33. A process for preparing a filler-reinforcedpolyamide composition having at least 25% by volume filler comprising(a) adding to a monomeric lactam, an inorganic siliceous filler having alength to diameter ratio of at least up to about 25 to 1, a somewhatrefractory nature with a melting point above about 800*C, a Mohs''hardness of at least 4, and a water solubility of less than 0.1 gram perliter, an organosilane coupling agent of the formula (R1O)3-Si-R-NH2where R1 is an alkyl group and R is an alkylene group having from about2 to 18 carbon atoms, and a lactam polymerization promoter, (b) removingvolatile reaction products if any, (c) holding the umpolymerized mixturefor an indefinite period of time. (d) adding a lactam polymerizationcatalyst, (e) casing the resultant mixture into a mold, and (f)maintaining the mixture at a temperture and for a time sufficient toachieve polymerization.
 34. A reinforced polyamide article comprising apolyamide and at least 25% by volume of an inorganic filler materialhaving a length to diameter ratio of up to about 25 to 1 and a watersolubility of less than 0.15 grams per liter, said material having beentreated with an organosilane coupling agent of the formula
 35. Areinforced polyamide article according to claim 34, said articlecharacterized by a Strength Index at least triple that of anequivalently filled but uncoupled article and a flexural modulus atleast double that of an unfilled article made from the base polyamideresin.
 36. A reinforced polymeric composition according to claim 17wherein said polyamide is a polylactam.
 37. A reinforced polymericcomposition according to claim 17 wherein said polyamide is acondensation product of a polyamine and a polycarboxylic acid.
 38. Areinforced polymeric composition according to claim 1 wherein saidfiller is a crystalline silica having a maximum particle size of about 5microns and an average particle size of about 2 microns.
 39. Areinforced polymeric composition according to claim 1 wherein saidcoupling agent has the formula X3-Si-R-Z where X is halogen or alkoxy, Ris an alkylene group having from about 2 to 18 carbon atoms, and Z isamino, secondary amido, isocyanato, alkoxycarbonyl or epoxy.
 40. Areinforced polymeric composition comprising a polyamide and from about33 to 67% by volume of an inorganic siliceous filler material which ischaracterized by a 3-dimensional crystal structure, a somewhatrefractory nature with a melting point above about 800*C, a Mohs''hardness of at least 4, a water solubility of less than about 0.1 gramper liter and a length to diameter ratio from about 1:1 up to about20:1, said filler material having been treated with an organosilanecoupling agent of the formula X3-Si-R-Z where X is halogen or alkoxy, Ris an alkylene group having from about 2 to 18 carbon atoms, and Z isamino, secondary amido, isocyanato, alkoxycarbonyl or epoxy, saidreinforced polymeric composition being characterized by a Strength Indexat least triple that of an equivalently filled but uncoupled compositionand a flexural modulus at least double that of the base resin.
 41. Areinforced polymeric composition according to claim 1 wherein saidfiller has a Mohs'' hardness of at least
 4. 42. A reinforced polymericcomposition according to claim 41 wherein said filler has been treatedwith an organosilane coupling agent having the formula X3-Si-R-Z where Xis alkoxy having up to 8 carbon atoms, R is an alkylene group havingfrom about 2 to about 18 carbon atoms and Z is amino.
 43. A reinforcedpolymeric composition according to claim 42 wherein said coupling agentis 3-triethoxysilylpropyl amine.
 44. A reinforced polymeric compositionaccording to claim 43 wherein the polyamide is polycaprolactam.
 45. Areinforced polymeric composition according to claim 43 wherein thepolyamide is polyhexamethylene adipamide.